Annoyingly tiny fridges may not be restricted to hotels or dorm rooms much longer. A new study proposes a way to construct the smallest refrigerator yet, based on just a few particles and capable of cooling to near absolute zero.

The study, which will appear in an upcoming issue of Physical Review Letters, pushes the limits of how small a cooling device can get and still remain functional.

"When thermodynamics was first invented, it was applied to big, steam engine sorts of things," says physicist Tony Short of the University of Cambridge in England, who was not involved in the study. "The fact that you can bring the ideas all the way down to individual quantum systems of tiny dimensions and the same basic ideas still work is quite nice."

Study coauthors Noah Linden, Sandu Popescu and Paul Skrzypczyk, all of the University of Bristol in England, propose a cooling scheme that relies on three linked qubits — particles that can exist in one of two states. Two of these qubits make up the refrigerator and would be held in two different heat baths: one very hot and one near room temperature. The third qubit is the object to be cooled. Because these qubits share a quantum connection, they can influence one another. So, as the hottest qubit absorbs energy from its toasty bath, it triggers the tepid qubit to siphon energy off the third qubit, cooling it. This extra energy dissipates off the second qubit in the same way the coil at the back of a refrigerator in the kitchen emits heat.

In their calculations, the physicists found that as the bath of the hottest qubit got hotter, the cooling ability of the fridge got better. And in principle, as long as the heat bath stays hot, the system can run forever. "Once you set it up, it just sits there, gently cooling away," Linden says.

Other small systems have been created, but this is the first that doesn't rely on external mechanisms, such as sophisticated lasers. "The whole guts of the fridge, it's all accounted for and not hidden in some macroscopic object which is really doing the work," Linden says.

Linden and his team also propose an even smaller system, in which a single particle with three distinct levels of quantum information, called a qutrit, acts as the refrigerator. "We believe this is the smallest possible thing you can call a fridge," Linden says.

Physicist Nicolas Gisin of the University of Geneva says the new study is "extremely elegant. It opens a totally new avenue for interesting questions, combining thermodynamics and quantum information science in a very original way."

The researchers plan to collaborate with other groups to settle on an exact blueprint for the minifridge and to build it. In the future, a tiny fridge might be used to slow or speed up reactions between proteins in cells by cooling precise parts, or to keep delicate components in quantum computers frigid.

A particularly fascinating question is whether such fridges might already exist in nature, Gisin says. For instance, a sun-drenched plant could have molecules with one end sitting directly in a natural thermal bath, allowing a tiny refrigerator to cool the other end.

Linden and his colleagues also find that idea exciting, but he's careful to point out that so far, it's just an idea. "We don't want to claim that we know of a place where this happens," he says. "But it would be great if someone came up with a molecule and said, 'Look at this. Doesn't it have the characteristics you need?' We'd be really, really happy if that happened."

This animation using data from observatories and amateurs around the world plots the positions of all the known asteroids in the solar system in 1980, and adds new ones as they are discovered. The pace and patterns of asteroid discovery give a neat visual illustration of the history of solar system exploration.

New asteroids appear in flashes of white, to make them easy to pick out. The final color codes for how close the object comes to Earth: Asteroids that cross Earth's orbit are shown in red, "Earth approachers" that come to 1.3 times the Earth-sun distance are yellow, and all others are green. The bunches of new asteroids follow Earth in its orbit, usually in the region directly opposite the sun (that is, in the Earth's night sky). Some clusters appear on the line between Earth and Jupiter, the side effects of surveys looking for Jovian moons.

In the mid-1990s, the pace of discovery picks up, showing the results of automated sky surveys. By 2001, the area just outside the orbit of Mars is filled in by a bright green ring of asteroids, and it keeps getting denser.

The beginning of 2010 brings a new pattern of discovery, with new asteroids fanning out on either side of the Earth. This new pattern is thanks to the Widefield Infrared Survey Explorer, an infrared space telescope that is expected to find hundreds of new asteroids by seeking their heat rather than their light.

According to the YouTube notes, "Currently we have observed over half a million minor planets, and the discovery rates snow no sign that we're running out of undiscovered objects."

The video was created using the 'astorb.dat' data created by astronomer Ted Bowell of the Lowell Observatory and colleagues.

CORRECTION: The original version of this article attributed the data to the Arecibo Observatory in Puerto Rico. It actually came from observatories all over the world, and was compiled by the Minor Planet Center and the Lowell Observatory.

This amoeba-shaped depression on Mars, called Orcus Patera, has had planetary scientists scratching their heads for decades. Despite these sharp new images from the European Space Agency's Mars Express spacecraft, the crater's origin is a complete mystery.

Orcus Patera, discovered in 1965 by the Mariner 4 spacecraft, is located near Mars' equator, between the volcanoes Elysium Mons and Olympus Mons. At 236 miles long, it would stretch from New York to Boston on Earth. Its rim rises over a mile above the surrounding plains, and its floor lies 1,300 to 1,900 feet below its surroundings.

But in spite of lying between two volcanoes and its designation as a patera — the name for deep, complex or irregularly shaped volcanic craters — scientists aren't at all sure that Orcus Patera has a volcanic origin story. It could be a large impact crater that was originally round but later deformed by compressional forces. Or it could have formed after the erosion of aligned impact craters. The most likely explanation is that it was made in an oblique impact, when a small body struck the surface at a very shallow angle, like a rock skipping on a pond.

The new images show that the crater's rim is criss-crossed by rift-valley-like structures called graben, which are evidence for active tectonic forces in the area. Smaller graben are also visible inside the depression itself, suggesting that several tectonic events have stretched the ground. The depression also shows "wrinkle edges," which indicate that the ground has been compressed as well as stretched. The dark shapes near the center of the depression were probably formed when dark material dug up by small impacts in the depression was blown around by the wind.

But these features all appeared after Orcus Patera was formed. The oblong crater's origin is still a mystery.

Images: ESA/DLR/FU Berlin (G. Neukum). More images available on the ESA website

As scientists get used to the idea that Earth is in a new geological age, that the Holocene — the last geological age — has been replaced by Anthropocene, they're figuring out how it got to be that way.

Two years ago, ecologists Erle Ellis and Navin Ramankutty at the University of Maryland, Baltimore County, released a map of the world's biological areas, traditionally known as biomes. Similar maps were found on science classroom walls across the land, but theirs was different in one very fundamental way: They updated the definition of biome to reflect how human beings used the land.

Ellis and Ramankutty said this was much more relevant to the 21st century, with more than six billion people using more of Earth's water, energy and matter than any other species, than classical biomes that didn't account for humanity's influence. They called their newly-defined areas "anthromes," short for anthropological biomes. It was a map for the anthropocene.

During a subsequent presentation, someone asked the researchers for details on how the anthropocene evolved. To answer that question, Ellis and Ramankutty have come out with a new set of maps that show how anthromes have changed since the beginning of the Industrial Revolution.

"You now have a biosphere that's completely transformed by people. Biology goes on in the human context, not the natural," he said. "And given the idea that most of ecosystem form and process is created by and ruled by human activity, how did it get to be that way?"

Published in the September Global Ecology and Biogeography, the maps show that in 1700, humans had already penetrated almost every habitable area. Then as now, people-free wilderness existed mostly in deserts and tundra. But in 1700, there was lots of "seminatural" land — used by people, but not heavily. Now there's little of that, and much of what remains is embedded within intensively used landscapes.

In future studies, the researchers want to overlay the anthrome map with other ecological metrics, such as biodiversity and biomass production.

The researchers' work raises philosophical and ethical questions about the difference between natural and wild, and the value of nature. In Ellis' view, the difference is irrelevant, and nature has precisely the value assigned it by people.

But whatever the answers are, "The main thing is, people need to be aware of their impacts and benefits on nature," said Ellis.

Images: 1) Global anthrome maps in 1700 and 2000./Global Ecology and Biogeography. 2) Map of land use intensity change between 1700 and 2000./Global Ecology and Biogeography. 3) Graph of global anthrome proportion change between 1700 and 2000./Global Ecology and Biogeography.

Some 58 undergrads were invited to a lab filled with spotless new equipment. Half of the students were asked to clean their hands with antiseptic wipe, so as not to soil the shiny surfaces. Afterward all the students rated the morality of six societal issues — smoking, illegal drug use, pornography, profane language, littering and adultery — on an 11-point scale ranging from very moral to very immoral. Those who'd wiped their hands made far-harsher judgments than those who didn't.

"Participants who cleansed their hands before rating the social issues judged these issues to be more morally wrong compared to those who did not cleanse their hands," the researchers report.

In a follow-up study, hundreds of participants were told to read a short passage that began, "My hair feels clean and light. My breath is fresh. My clothes are pristine and like new," made harsher moral judgments about 16 social issues compared to those primed to feel dirty by reading a passage that read, "My hair feels oily and heavy. My breath stinks. I feel so dirty."

A third study was identical to the second, except that after reading either the dirty or clean passage of text, the 136 undergrad participants also ranked themselves against their peers on several factors including intelligence, attractiveness and moral character.

Those who held a self-image of cleanliness and purity made more harsh moral judgements on social issues. Crucially, this association was entirely mediated by their having an inflated sense of moral virtue compared with their peers. (By contrast, reading the clean vs. dirty text made no difference to self -rankings on the other factors).

"Acts of cleanliness have not only the potential to shift our moral pendulum to a more virtuous self, but also license harsher moral judgment of others," Zhong and his team concluded.

A prehistoric man whose naturally mummified body was discovered frozen in the Italian Alps may have been toted up the mountain by his comrades, a new study suggests.

The Iceman, also nicknamed Ötzi, lived between 5,350 and 5,100 years ago as part of a genetically distinct European population. Hikers noticed the Iceman poking out of a glacier in 1991.

Since the 2001 discovery of a stone point in the Iceman's left shoulder, many scientists have assumed that someone shot and killed Ötzi with an arrow as he attempted to flee through a mountain pass after a disastrous fight. From this perspective, the Iceman preserves a brutal prehistoric moment in time.

But a new analysis of the distribution of Ötzi's belongings around his body, published in the September issue of Antiquity, raises the possibility that he perished near kin living at low altitudes, who took him to the mountains for a final send-off as soon as the weather permitted.

Ötzi originally was placed on a group of stones that formed a platform about 20 feet uphill from the spot where hikers found him splayed in a gully, assert archaeologist Alessandro Vanzetti of the Sapienza University of Rome and his colleagues. Snow and ice that originally held the body in place partly thawed during occasional warm periods, creating a watery mix that swept the Iceman and some of his effects, including a wooden bow and copper ax, off the platform, the scientists propose.

The body then gradually rolled downhill. Lodged against a boulder in the gully, Ötzi's left arm twisted across his body at an odd angle, they assert.

"Many researchers have never questioned the 'disaster' theory of the Iceman's death, so they haven't searched for the original focus of scattering of the body and artifacts," says study co-author Luca Bondioli of the National Museum of Prehistory and Ethnography in Rome.

Archaeobotanist Klaus Oeggl of the University of Innsbruck, Austria, reported in 2000 that high concentrations of a binding material used in Ötzi's equipment appeared not just near his body but on a nearby ridge that includes the burial platform proposed by Vanzetti's team.

Oeggl agrees that warming and freezing cycles caused the Iceman's body to move from an initial resting place on the ridge to the gully. But no compelling evidence demonstrates that stones on the ridge were placed there to form a burial platform, he says.

Still, Oeggl says, "This new paper for the first time discusses a burial hypothesis in a substantial way."

Ötzi probably died in the mountains alone and close to where he suffered a fatal injury, argues biological anthropologist Albert Zink, head of the EURAC Institute for Mummies and the Iceman in Bolzano, Italy. The Iceman's joints and spine display no dislocations that would have resulted from a downhill slide. Intact blood clots in his arrow wound would show damage if the body had been carted up the mountain, Zink adds.

If Zink is correct, warming and freezing cycles should have randomly spread out his belongings, Bondioli counters. Instead, a mathematical analysis of the position of artifacts recovered around Ötzi reveals two main clumps of items, one at the proposed stone platform and another in the gully where his body lay.

A backpack frame rested on the platform, trapped by a protruding rock. Clumps of human and animal hair, plant fragments, splinters of arrow shafts and an ax lay nearby.

Remains of a grass mat, regarded as an overcoat by many investigators, were found near Ötzi's body. Vanzetti's group suspects the mat was part of a funeral shroud.

Ötzi's belongings include an unfinished wooden bow and arrow shafts lacking points, which make sense as burial offerings because a hunter could not have used them, the researchers add.

Move over solar, wind and wave power — there's a new renewable on the block. Researchers are experimenting with devices that can pull electricity from the air.

For centuries, scientists have been fascinated by the idea of harnessing the power of thunderstorms. Nikola Tesla experimented extensively with the topic, but significant understanding of the field of atmospheric electrodynamics has until recently proved elusive.

Fernando Galembeck, of the University of Campinas in Brazil, presented a report at the 240th National Meeting of the American Chemical Society that detailed a future where every house has a device on its roof that pulls cheap, clean electricity out of the air. "Just as solar energy could free some households from paying electric bills, this promising new energy source could have a similar effect," he said.

Originally, scientists believed that water droplets in the atmosphere were electrically neutral, and remained that way even after brushing up against charges on dust particles and other liquids. However, Galembeck discovered in a series of lab experiments that water droplets do in fact pick up a charge.

He used particles of silica and aluminum phosphate, both of which are common dust particles in the air, and found that they become increasingly charged as the amount of water vapor in the air increases. "This was clear evidence that water in the atmosphere can accumulate electrical charges and transfer them to other materials it comes into contact with," said Galembeck.

It could be possible to harvest this "hygroelectricity" from the air in regions that experience high humidity, such as the tropics. To jump-start this industry, Galembeck's team is already testing metals to see which might be of most use in capturing atmospheric electricity on hygroelectric panels.

A similar approach could help to avert lightning damage, too, by placing hygroelectric panels on buildings to take charge out of the air in the vicinity of places that suffer regular thunderstorms. "These are fascinating ideas that new studies by ourselves and by other scientific teams suggest are now possible," said Galembeck.

"We certainly have a long way to go. But the benefits in the long range of harnessing hygroelectricity could be substantial."

SEATTLE — Snowball the dancing parrot doesn't just bob to the beat. The YouTube sensation, who proved last year that humans aren't the only species that got rhythm, gets his groove on better with a dance partner.

For the famous sulfur-crested cockatoo, it's about bonding with his human caretaker, Irena Schultz. Snowball became an online celebrity in 2007 after Schultz, who runs the Bird Lovers Only Rescue Service in Indiana, put a video of him dancing to "Everybody" by the Backstreet Boys up on YouTube.

Two papers in Current Biology in May 2009 showed that Snowball — plus a total of 14 species of parrots and one species of elephant — move rhythmically to music in a way that other animals don't, demonstrating that dancing is not uniquely human. The ability to dance could come from a connection between the auditory centers and the motor centers in avian and human brains, which allows for speech and lays the foundation for synchronizing our bodies to music.

But some species of songbirds have this same neural connection — yet don't dance. Other, more social birds, like crows, sometimes synchronize their movements with their long-term mates. Patel and his colleagues wondered if Snowball's dancing has a social side.

In an experiment they called the "Dancing With Myself" test, Patel and his colleagues played music for Snowball when he was alone, when Schultz was in the room but not dancing, and when Schultz danced along with him. Naturally, the songs the team chose included Billy Idol's "Dancing With Myself," along with "Jenny (867-5309)" by Tommy Tutone and a song by Pink. The researchers tracked how much time Snowball spent dancing in each case, as well as how enthusiastic he seemed.

"We got Mack truck results," Patel said. When "Dancing With Myself" and "Jenny" played, Snowball spent about twice as much time dancing when Schultz was in the room than when he was alone, and danced more than twice as often as that when Schultz moved to the music too. For the Pink song, Snowball spent about as much time dancing alone as when Schultz was present, but again doubled his movements when Schultz joined in.

"There's some mutability here, but having a partner makes him much more likely to dance," Patel said.

In a second study, Schultz danced to a different drummer. Schultz wore headphones that played the same song Snowball heard, but at a different tempo, to see whether Snowball would follow the music or his bad dance partner.

When Schultz danced to the wrong beat, Snowball appeared confused. Eventually he turned around and ignored Schultz, dancing to his own music until close to the end of the song. When he turned to face her again, his leg-lifts were less high and his head bobs less sure. "He's less enthusiastic, more tentative," Patel said.

Unfortunately, Schultz got sick and had to postpone the study before the team could collect enough data to draw confident conclusions, Patel said. But "the bottom line is, social context matters in avian movement to music," he said. "Maybe that's why only a subset of vocal learners move rhythmically to music."

The idea "makes sense intuitively," said psychologist Charles Snowdon of the University of Wisconsin-Madison, who has studied music written specially for monkeys but was not involved in the new work. "It's a really interesting demonstration that begs for more studies."

The fact that research had to stop when Snowball's caretaker got sick — that "when the owner can't function, the bird can't function" — especially supports the idea that dancing is social for Snowball, Snowdon added. "That almost proves his point right there."

The videos from that experiment won't be available until the study is published in a scientific journal, Patel said, but Schultz and Snowball were filmed dancing together to Lady Gaga's "Bad Romance" at the Midwest Bird Expo in Illinois on May 22.

On Aug. 22, airport security officials in Bangkok detected something suspicious in an oversize suitcase. X rays indicated that along with stuffed animals, the bag contained bones. Indeed, they belonged to a tranquilized two-month-old tiger. The bag, which had been checked by a 31-year old Thai woman, had been en route to Iran.

The cargo was confiscated and the cub is now under the protection of Thailand's Department of National Parks, Wildlife and Plant Conservation, according to Traffic International, a British-based conservation group committed to shutting down international trade in threatened and endangered species. DNA testing of the animal is currently underway to determine its subspecies, which may offer clues to whether it had been poached from the wild or reared in captivity.

The transshipment of wildlife through Bangkok is one reason U.S. AID has provided financial backing for training of security officers and police as part of a "Wildlife Trafficking Stops Here" campaign at this airport. Earlier this year, some 250 individuals took part in the training.

"Traffic is glad to see these training programs pay off in seizures, arrests and continued vigilance at the airport," notes Chris Shepherd, regional director for the conservation group in Southeast Asia. However, he adds, the fact that people think they can move wildlife through checked baggage suggests "they obviously think wildlife smuggling is something easy to get away with." The remedy, he argues, will be more-aggressive monitoring and far tougher penalties for scofflaws.

The Indonesian mimic octopus has the boldest defense strategy of any of its cephalopod cousins, and now scientists know how that strategy evolved. Rather than blending into the scenery, the octopus mimics the swimming behavior and shape of a variety of toxic sea creatures — like flatfish and sea snakes — and displays bold color patterns that shock predators.

Scientists have reconstructed the family tree and unique evolution of the Indonesian mimic octopus, Thaumoctopus mimicus, using DNA sequences from 35 of its relatives. The study will be published in September in Biological Journal of the Linnaean Society.

For the study, scientists focused on mimic's ability to swim on the sea floor like a flatfish, of which there are several toxic varieties in the region where the octopus lives (video above). The analysis revealed that the behavior evolved in three key steps.

First, mimic octopus ancestors started switching on bold colors to shock predators when camouflage failed. Next, they learned to swim like sea-floor–dwelling fish and developed longer arms that facilitate the motion. Third, they combined the bold color patterns and flatfish swimming technique, and started doing it while out on daily forays and resting.

"While T. mimicus' imitation of a flatfish is far from perfect, it may be good enough to fool predators where it lives, in the world's center of marine diversity," biologist Healy Hamilton of the California Academy of Sciences, co-author of the study, said in a press release. "In the time it takes a predator to do a double-take, the octopus might be able to get away."

The Indonesian mimic octopus was first discovered by scientists in 1998.